The field of the invention relates generally to rotary machines, and more particularly, to rotary machines including active magnetic bearing (AMB) systems.
Active magnetic bearing systems are used in rotary machines for providing non-contact support of a rotating piece, i.e., a rotor. Sometimes the rotor experiences loads that are greater than the capacity of the active magnetic bearing system. Accordingly, rotary machines include auxiliary mechanical bearings, i.e., landing bearings, to receive the rotor when the loads on the rotor exceed the capacity of the active magnetic bearing system. However, the loads on the rotor that exceed the capacity of the active magnetic bearing system result in contact between the landing bearings and the rotor, i.e., rotor landings.
Sometimes, the rotary machines experience conditions that may introduce loads approaching, and potentially exceeding, the design capacity of the active magnetic bearing system and increase a potential for rotor landings. At least some known rotary machines include a localized controller to account for high dynamic loads. However, the localized controllers are inefficient in accounting for some load variations. In addition, the localized controllers do not account for high static loads such as those introduced by, e.g., near choke area or high volume flow area conditions associated with a compressor. Moreover, at least some known controllers operate within long-term operating parameters that limit the performance and efficiency of the rotary machine.